Delivering Traumatic Brain Injury to Larval Zebrafish

We describe a straightforward, scalable method for administering traumatic brain injury (TBI) to zebrafish larvae. The pathological outcomes appear generalizable for all TBI types, but perhaps most closely model closed-skull, diffuse lesion (blast injury) neurotrauma. The injury is delivered by dropping a weight onto the plunger of a fluid-filled syringe containing zebrafish larvae. This model is easy to implement, cost-effective, and provides a high-throughput system that induces brain injury in many larvae at once. Unique to vertebrate TBI models, this method can be used to deliver TBI without anesthetic or other metabolic agents. The methods simulate the main aspects of traumatic brain injury in humans, providing a preclinical model to study the consequences of this prevalent injury type and a way to explore early interventions that may ameliorate subsequent neurodegeneration. We also describe a convenient method for executing pressure measurements to calibrate and validate this method. When used in concert with the genetic tools readily available in zebrafish, this model of traumatic brain injury offers opportunities to examine many mechanisms and outcomes induced by traumatic brain injury. For example, genetically encoded fluorescent reporters have been implemented with this system to measure protein misfolding and neural activity via optogenetics.

Full-field exposure of larval zebrafish to narrow waveband LED light sources at defined power and energy for optogenetic applications

BACKGROUND

Optogenetic approaches in transparent zebrafish models have provided numerous insights into vertebrate neurobiology. The purpose of this study was to develop methods to activate light-sensitive transgene products simultaneously throughout an entire larval zebrafish.

NEW METHOD

We developed a LED illumination stand and microcontroller unit to expose zebrafish larvae reproducibly to full field illumination at defined wavelength, power, and energy.

RESULTS

The LED stand generated a sufficiently flat illumination field to expose multiple larval zebrafish to high power light stimuli uniformly, while avoiding sample bath warming. The controller unit allowed precise automated delivery of predetermined amounts of light energy at calibrated power. We demonstrated the utility of the approach by driving photoconversion of Kaede (398 nm), photodimerization of GAVPO (450 nm), and photoactivation of dL5**/MG2I (661 nm) in neurons throughout the CNS of larval zebrafish. Observed outcomes were influenced by both total light energy and its rate of delivery, highlighting the importance of controlling these variables to obtain reproducible results.

COMPARISON WITH EXISTING METHODS

Our approach employs inexpensive LED chip arrays to deliver narrow-waveband light with a sufficiently flat illumination field to span multiple larval zebrafish simultaneously. Calibration of light power and energy are built into the workflow.

CONCLUSIONS

The LED illuminator and controller can be constructed from widely available materials using the drawings, instructions, and software provided. This approach will be useful for multiple optogenetic applications in zebrafish and other models.

Sinusoidal analysis reveals a non-linear and dopamine-dependent relationship between ambient illumination and motor activity in larval zebrafish

Larval zebrafish show stereotyped motor responses to changes in ambient illumination. The responses can be evaluated in 96-well plates, and are used widely to assess neurological function in zebrafish models. However, the square-wave (on/off) light stimuli commonly employed in these studies do not allow analysis of the relationship between motor activity and illumination intensity or its rate of change. To address this limitation, we measured larval zebrafish motor function while ambient illumination was modulated sinusoidally. Motor activity varied robustly and reproducibly in antiphase with illumination. The relationship between mean swimming speed (dependent variable) and illuminance (independent variable) was described most closely by a power function, and was influenced dynamically by the proportional rate of change of illuminance. Several predictions from this model were verified experimentally by testing responses to sinusoidal illumination waveforms that were amplitude-, phase-, or offset-modulated, or transformed by a power function. At concentrations ≤5 μM, the dopamine D2 receptor inverse agonist haloperidol selectively abrogated the motor response to decreasing Illuminance without altering baseline activity in bright light, suggesting that dopamine is essential for illuminance-dependent motor function. These data contribute to understanding the environmental determinants of motor activity in zebrafish larvae, suggest experimental opportunities to elucidate underlying neural mechanisms, and potentially provide an assay of dopaminergic function for chemical and genetic screening applications.

Provisional country estimates of prevalent adult human immunodeficiency virus infections as of end 1994: a description of the methods

BACKGROUND

A country-by-country review of human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) data was undertaken by the World Health Organization. This paper describes the methods used to make estimates of HIV prevalence.

RESULTS

It is estimated that, globally, approximately 16.9 million adults were living with HIV infections at the end of 1994. The majority (66%) of the infections were in sub-Saharan Africa (over 11000000), followed by South and South East Asia (over 3000000). Estimated prevalence rates for HIV infection ranged from less than 1 per 100000 sexually active adult population to 18 per 100 (18%), with a median prevalence of 14 per 10000. In 50 countries the estimated HIV prevalence rate was less than 5 per 10000 sexually active adults. In 15 countries (all in sub-Saharan Africa) the prevalence rate was above 5%. The lowest estimated prevalence rates were seen in Central and East Asia and the highest in Central and Southern Africa.

CONCLUSIONS

Estimates of prevalent HIV infections are intended to give an indication of the magnitude of the HIV pandemic but, due to the difficulties in accurately assessing the levels of HIV infections in national populations, should be considered provisional.

Epi Info: a general-purpose microcomputer program for public health information systems

Epi Info is a general-purpose set of computer programs for word processing, database management, statistics, and graphics developed over the past five years at the Centers for Disease Control and the World Health Organization. The programs allow rapid questionnaire construction, data entry, and analysis during epidemic investigation. Both data entry and analysis can be programmed to provide customization and automatic operation for more permanent systems, such as those for disease or injury surveillance. Epi Info is in the public domain and copies may be freely distributed. It requires an IBM-compatible micro-computer with at least 512 kilobytes of memory. Translations into French and Spanish are in progress; a translation kit is available to facilitate translation into other languages.

Hepatitis B virus infection among children born in the United States to Southeast Asian refugees

Since 1975 nearly 1 million persons have entered the United States from Southeast Asia, where infection with hepatitis B virus (HBV) is hyperendemic. To evaluate the prevalence and patterns of transmission of HBV infection among the children of refugees from Southeast Asia, we studied 196 refugee families with 257 children born in the United States. Of 31 children born in the United States to mothers with infectious disease, 17 (55 percent) had been infected with HBV. Of 226 children whose mothers did not have infectious disease, 15 had HBV infection--a prevalence of 6.6 percent (95 percent confidence interval, 4.1 to 10.7). The risk of infection was greatest (26 percent) among children living in households with children with infectious disease (relative risk, 5.5; confidence interval, 2.3 to 13.4). Exposure to fathers or other adults with infectious disease was not significantly associated with infection. Of children from households with no persons with infectious disease, 3.9 percent (confidence interval, 1.7 to 8.8) were infected. Nearly half (46 percent) the cases of HBV infection among the U.S.-born children of refugees were not attributable to perinatal transmission from a mother with infectious disease. We conclude that child-to-child transmission may be occurring within and between households. Current recommendations to immunize the newborns of mothers with infectious disease are not sufficient to protect all U.S.-born children of Southeast Asian refugees from HBV infection early in life, when the risk of chronic sequelae and premature death is highest. We recommend that the HBV vaccination policy be expanded to include all newborns of Southeast Asian immigrants.

Alcohol and fatal injuries: temporal patterns

Although alcohol use has been established as a risk factor for injuries associated with motor vehicle crashes, the role of alcohol for other unintentional and intentional injuries is less defined. A review of 102,401 deaths investigated by North Carolina medical examiners in the period 1973-1983 characterized the temporal patterns of ethyl alcohol in unintentional injury fatalities, suicides, homicides, and persons who died of natural or unknown causes. Victims of homicides (85.9%) and suicides (77.7%) were tested for alcohol more frequently than were fatalities resulting from unintentional injury (67.5%) or natural causes (61.6%). Alcohol was present in 62.8% of homicide victims, 48.6% of unintentional injury fatalities, 35.3% of suicides, and 14.4% of deaths from natural causes. The percentage of alcohol-associated deaths for each manner of death showed little yearly or seasonal variation. Alcohol was most frequently detected in persons fatally injured on the weekend and from 6 PM to 6 AM. This study highlights the magnitude of alcohol's role in intentional and unintentional injuries, especially for persons injured at night and on weekends.

The Epidemiologic Surveillance Project: a computer-based system for disease surveillance

The Epidemiologic Surveillance Project (ESP) is a computer-based surveillance system for the rapid transmission and analysis of national morbidity data. These data are transmitted weekly by state health department computers to the Centers for Disease Control (CDC), using a commercial electronic mail facility (MINET). Participating state health departments transmit data through existing computer systems using a standard record and data transmission protocol. State and national data are rapidly analyzed at the CDC, and reports of these analyses are transmitted through MINET to the states. Maps based on these data and other tabular displays of demographic and epidemiologic characteristics of the diseases being tracked are periodically prepared and distributed. Because the efficiency, speed, and uniformity of tabulation of this system are greater than those of systems that use protocol and telephonic reports of case totals, the ESP may be a model for future surveillance systems.

The impact of publicly funded perinatal care programs on neonatal outcome, Georgia, 1976-1978

The State of Georgia administers three publicly funded perinatal care programs for medically high risk and/or low-income women: the High Risk Pregnancy Program, the Medicaid Program, and the Maternal and Infant Care Projects. To assess the impact of these programs on infant health, we compared the birth weight distribution and neonatal mortality rates of infants born to women in each program with those of infants of a nonfunded group of women with less than 12 years' education. Infants of women in publicly funded groups were more likely to weigh less than or equal to 2,500 gm at birth than those of women in the nonfunded group. Neonatal mortality rates for publicly funded groups were similar to those of the nonfunded group. The neonatal mortality rates for infants of birth weight less than or equal to 2,500 gm of publicly-funded women were significantly lower than those of the nonfunded women. There were no significant differences between groups for neonatal mortality rates for infants of birth weight greater than 2,500 gm. These findings suggest that publicly funded perinatal care programs may improve neonatal survival of infants of birth weight less than or equal to 2,500 gm of low-income mothers.